The Microsoft Natural Keyboard is an ergonomic keyboard for computers, introduced in 1994. It was designed for Microsoft by Ziba Design. The keyboard was a split keyboard with each half of the keyboard separated and tilted upwards and down from the center of the keyboard. This key arrangement was ergonomically designed to prevent carpal tunnel syndrome and other repetitive strain injuries associated with typing for long periods of time. Another innovation was the integrated wrist pad helping to ensure correct posture while sitting at the computer and further reducing strain on the neck, arms and wrists. This keyboard also introduced three new keys purposed for Microsoft's upcoming operating system: two Windows logo keys between the Ctrl and Alt keys on each side, and a Menu key between the right Windows and Ctrl keys. Although it was not the first ergonomic keyboard, it was the first widely available sub-$100 offering. The keyboard gained popularity quickly, selling over 600,000 per month at its peak.